<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>

  <body>
    <style>
      #container {
        top: 100px;
        left: 100px;
        position: relative;
        width: 100px;
        height: 100px;
        background-color: skyblue;
      }
    </style>
    <div id="container"></div>
    <div>
      <button id="btnGet">获取</button>
    </div>
    <script>
      btnGet.addEventListener("click", function () {
        const rect = container.getBoundingClientRect();
        console.log(rect);
      });
    </script>
  </body>
</html>
